It's a little hiccup during map rework. Fortunately, it is easy to fix.
Go in the mods\Piratez\Ruleset\Piratez_faction.rul file
Look for the following block:
- type: STR_LOC_ELFMAN_BROS
alert: STR_ALERT_BOUNTY_HUNT_B
alertBackground: RAID_BACKGROUND.SCR
alertDescription: STR_LOC_ELFMAN_BROS_BRIEFING
briefing:
palette: 2
background: RAID_BACKGROUND.SCR
showTarget: false
title: STR_LOC_ELFMAN_BROS_TITLE
desc: STR_LOC_ELFMAN_BROS_BRIEFING
markerName: STR_MARKER_LOC_ELFMAN_BROS
duration: [25, 50]
width: 60
length: 60
height: 10
turnLimit: 20
chronoTrigger: 1 #(0-lose, 1-abort, 2-win)
enviroEffects: STR_ENVIRO_ENEMY_UNBREAKABLE
spawnUfo: STR_LOC_ELFMAN_BROS
Replace with:
- type: STR_LOC_ELFMAN_BROS
alert: STR_ALERT_BOUNTY_HUNT_B
alertBackground: RAID_BACKGROUND.SCR
alertDescription: STR_LOC_ELFMAN_BROS_BRIEFING
briefing:
palette: 2
background: RAID_BACKGROUND.SCR
showTarget: false
title: STR_LOC_ELFMAN_BROS_TITLE
desc: STR_LOC_ELFMAN_BROS_BRIEFING
markerName: STR_MARKER_LOC_ELFMAN_BROS
duration: [25, 50]
width: 60
length: 60
height: 10
turnLimit: 20
chronoTrigger: 1 #(0-lose, 1-abort, 2-win)
enviroEffects: STR_ENVIRO_ENEMY_UNBREAKABLE
customUfo: STR_LOC_ELFMAN_BROS
(tl;dr: change the last line from "spawnUfo" to "customUfo")